Device for clamping the trailing end portion of a sheet

ABSTRACT

A device comprising a groove-shaped clamp member receiving portion formed in one part of the periphery of a drum and disposed parallel to the axis of the drum, and an elongated clamp member adapted to be received in the groove-like receiving portion. The device is effective to clamp the trailing end portion of a sheet to the drum by tightly holding the trailing end portion in place by means of the clamp member cooperating with the groove-shaped receiving portion after the leading end portion of the sheet is gripped by grip means while the drum is rotating.

United States Patent 11 1 I l I 1 3,903,795

Suzuki Sept. 9, 1975 [5 DEVICE FOR CLAMPING THE TRAILING 3.513.772 5/1970 Brasty 101/4151 x 3,664,260 5/1972 Millcret al, 101/4151 x END PORTION OF A SHEET [75] Inventor: Minoru Suzuki, Yokohama, Japan [73] Assignee: Ricoh Co., Ltd., Tokyo. Japan [22] Filed: May 30, 1973 [21 Appl. No; 365,084

[30] Foreign Application Priority Data June 17. [972 Japan 4760714 [52] US. Cl r. 101/409; 101/415] [51] Int. Cl. B4lF 21/04 [58] Field ofSearch 1. [OI/451L408, 409,410

[56] References Cited UNITED STATES PATENTS 2,822,754 2/1958 Huck 1 1 1 l 4 4 10l/415.l 2,861,862 ll/l958 Zccha ct al lUl/4l5.l X 3,348,288 10/1967 Tanguay ct al. [Oi/415.1 X 3.46:0,443 X/l969 Sarka ct a1 lU1/4l5.l X

Primary Examiner-Edgar S. Burr Assisran! Examiner-Paul J. Hirsch Attorney, Agent, or FirmCooper, Dunham. Clark, Griffin & Moran [57] ABSTRACT A device comprising a groove-shaped clamp member receiving portion formed in one part of the periphery of a drum and disposed parallel to the axis of the drum, and an elongated clamp member adapted to be received in the groove-like receiving portion. The device is elfective to clamp the trailing end portion of a sheet to the drum by tightly holding the trailing end portion in place by means of the clamp member c0op erating with the grooveshaped receiving portion after the leading end portion of the sheet is gripped by grip means while the drum is rotating.

5 Claims, 22 Drawing Figures PATENTED SEP 9|975 SHEET 1 0F FIG.

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DEVICE FOR CLAMPING THE TRAILING END PORTION OF A SHEET BACKGROUND OF THE INVENTION This invention relates to a device for clamping the trailing end portion of a sheet which permits the sheet to be automatically mounted on a drum.

In carrying out printing by means of an offset dupli cating machine, for example, ink is applied to a master plate mounted on a master cylinder to form an ink image of the master sheet on a blanket cylinder, and a copy sheet is supplied between the blanket cylinder and an impression cylinder so that the ink image may be transferred from the blanket cylinder to the copy sheet. This operation will be described with reference to the prior art machines shown in FIGS. 1 through 3.

FIG. 1 schematically shows essential portions of an offset duplicating machine in which 1 is a master cylinder on which one of master plates 2 is mounted thereon. and 3 is a blanket cylinder to which an impression cylinder 4 is adapted to be brought into pressing engagement, with a copy sheet 5 being interposed between the blanket cylinder 3 and the impression cylinder 4. One of the master plates 2 on a plate feed tray 6 is supplied by a plate feed roller 7 to the master cylinder 1 and mounted on the periphery thereof. An etching solution I] is applied to the master plate 2 on the master cylinder 1 by a roller 9 of an etching device 8 (See FIG. 2). The etching solution is applied to the master plate so that ink may only adhere to image regions of the master plate 2 while non-image regions thereof remain free from ink.

After the etching solution is applied to the master plate 2, ink is applied thereto by an inking roller 13 of an inking device 12 to form an ink image of the master plate on the blanket cylinder 3. Thereafter copy sheets 5 are supplied one after another between the blanket cylinder 3 and impression cylinder 4 by a sheet feed roller 14 so that duplicates of the master plate 2 can be produced. Printed copy sheets are discharged from the printing apparatus 15. After a predetermined number of copy sheets have been printed, the master plate 2 mounted on the master cylinder 1 is discharged by a plate discharge roller 16 and ejected on to a plate discharge tray 17. At the same time the ink image on the blanket cylinder 3 is cleaned by a cleaning device (not shown).

In FIG. 2, grip claw means 18 is arranged in a recess la formed in the periphery of the master cylinder 1 to bring the leading end portion of the master plate 2 into pressing engagement with the periphery of the master cylinder 1 when the master plate 2 is mounted on the master cylinder I. In duplicating apparatus of the prior art. the leading end portion of the master plate 2 mounted on the master cylinder 1 is held tightly in position by the grip claw means as aforementioned. but its trailing end portion 2a is not clamped to the periphery of the master cylinder and is free to move.

When the etching solution 1] is applied to the master plate 2. the latter becomes limp so that it can be made to conform to the shape of the periphery of the master cylinder. Although the master plate can thus be brought into intimate contact with the periphery of the master cylinder, the trailing end portion of the master plate discngages the periphery of the master cylinder immediately after it is mounted on the master cylinder. so that the trailing end portion tends to come into contact with various devices disposed in the neighborhood of the master cylinder or the etching roller, inking roller. blanket cylinder and plate feed and discharge device, for example. As a result, the master plate tends to be soiled before printing is initiated.

in order to obviate this disadvantage it has hitherto been customary to apply the etching solution to the master plate before it is mounted on the master cylinder. This operation, which is generally referred to as a pre-etching operation, is generally performed manually. The conditions of the master plates treated by the pre-etching operation may vary from one master plate to another depending on the manner in which the operation is performed by different operators. [f the master plate is not thoroughly pre-etched, then its trailing end portion 2a is brought into contact with the inking roller 13 as shown in FIG. 2. As a result, ink adheres to nonimage regions of the master plate 2 and thus soils the plate, thereby interfering with the printing operation. in view of this, not only the leading end portion but also the trailing end portion should be positively clamped to the periphery of the master cylinder.

FIG. 3 shows essential portions of a duplicating machine provided with an electrophotographic copying apparatus adapted to prepare a master plate on the printing cylinder. The copying apparatus comprises a charging device 21, an exposing device 22 and a developing device 23 disposed around the master cylinder 1. A master plate 24 has on its surface an electrically insulating material layer which is uniformly charged by the charging device 21 as the master cylinder 1 rotates in the direction of an arrow. Then the charged surface of the master plate 24 is exposed to an optical image of an original (not shown) by the exposing device 22. As a result, an electrostatic latent image is formed on the master plate 24 and developed by the developing device 23 so that a visible image is formed on the master plate.

In this type of duplicating machines in which a printing master is prepared on the periphery of the master cylinder 1, the exposing of the plate to an optical image of an original can not be carried out satisfactorily unless a rear end portion 24a of the master plate 24 is maintained in intimate contact with the periphery of the master cylinder 1. Otherwise the image formed on the master plate may be blurred. It is therefore desirable to positively clamp the rear end portion of the master plate as by a clamp rod 25 or the like. It is necessary positively to clamp both the leading end portion and trailing end portion of a master plate to the master cylinder when the plate is going to be mounted on the rotating master cylinder and wound intimately thereon.

SUMMARY OF THE INVENTION This invention has as its object the provision of a clamp device which permits a sheet supplied to a rotating drum to be automatically and positively clamped at its leading end portion and trailing end portion to the periphery of the drum.

According to the invention, there is provided a clamp device comprising a sheet clamp member disposed in a clamp member receiving portion formed on the periphery of a rotating drum wherein a sheet can pass under the clamp member if the latter is moved upwardly to its inoperative position when the former is supplied to the drum and the trailing end portion of the sheet can be automatically clamped to the periphery of the rotating drum if the clamp member is moved downwardly to its operative position. By clamping the trailing end portion of the sheet to the drum. it is possible to eliminate the preetching operation which has hitherto been performed in offset duplicating machines and to prevent soiling of the sheet by the inking roller. The clamp device according to the invention is also effective to permit exposing of the sheet to an optical image of an original to be carried out satisfactorily to keep the image formed on the sheet from being blurred when a printing master is prepared on the rotating drum by means of an electrophotographic copying apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an offset duplicating machine;

FIG. 2 is a side view of a master plate mounted on a master cylinder with its trailing end portion not clamped to the cylinder;

FIG. 3 is a schematic view of a rotating master cylinder and portions of an electrophotographic copying apparatus used to prepare a printing master on the periphery of the rotating master cylinder;

FIG. 4 is a front view of the device for clamping the trailing end portion of a sheet comprising one embodiment of the invention;

FIG. 5 is a perspective view of the drum provided with the clamp device shown in FIG. 4;

FIG. 6 is a fragmentary sectional side view of the drum shown in FIG. 5, showing sheet grip claw means and sheet pushout means;

FIG. 7 is a front view of the sheet feed and discharge mechanisms adapted to feed a sheet to the drum and discharging the same therefrom;

FIG. 8 is a view of the drive system for driving sheet feed and sheet discharge rollers;

FIG. 9 shows the manner in which the sheet feed mechanism shown in FIG. 7 operates when a sheet is fed;

FIG. 10 shows the manner in which the sheet feed roller operates;

FIG. 11 shows the manner in which the sheet feed mechanism shown in FIG. 7 and the clamp device shown in FIG. 4 operate;

FIG. 12 is a front view of the clamp member and one of the side wall cams;

FIG. I3 shows the manner in which the clamp device shown in FIG. 4 operates;

FIG. 14 shows the manner in which the sheet discharge mechanism shown in FIG. 7 operates;

FIG. 15 is a front view of the guide roller;

FIG. 16 shows the manner in which the clamp device shown in FIG. 4 operates when a sheet is discharged;

FIG. I7 is a front view of the actuation roller and sheet discharge roller;

FIG. I8 shows the manner in which the clamp device shown in FIG. 4 operates when a sheet is discharged;

FIG. 19 is a front view of the clamp device comprising another embodiment of the invention, showing its essential portions;

FIG. 20 shows the manner in which the clamp device shown in FIG. 19 operates;

FIG. 2! is a front view of the clamp device compris ing another embodiment of the invention. showing its essential portions; and

FIG. 22 shows the manner in which the clamp device shown in FIG. 21 operates.

DESCRIPTION OF EMBODIMENTS The invention will now be described with reference to the embodiments shown in the drawings. In FIG. 4, a drum 41 interposed between right and left side plates (not shown) of the duplicating machine is supported by a shaft 42 for rotation in the direction of an arrow 43. A sheet feed cam 44 and a mounting plate 45 (See FIG. 5) are rotatably supported by the shaft 42 in addition to the drum 41.

One clamp member supporter 46 is disposed on one side of the drum 4] while the other clamp member supporter 47 is disposed on the other side of the drum 4] as shown in FIG. 5. The supporter 46 is formed therein with a plurality of slots 48, 48 loosely receiving therein shafts 49, 49 fixed to the sheet feed cam 44, so that the supporter 46 is mounted on the cam 44. The other supporter 47 is mounted on the mounting plate 45 in like manner. A clamp member SI which may be in the form of a rod is rotatably supported at its opposite ends by the supporters 46 and 47. A pair of compression springs 52 each connected at one end to the supporter 46 and at the other end to the sheet feed cam 44 and another pair of compression springs 53 each connected at one end to the supporter 47 and at the other end to the mounting plate 45 urge by their biasing forces the supporters 46 and 47 and the connected clamp member 51 into pressing engagement with the periphery of the drum 4].

As shown in FIG. 5 and FIG. 6, the drum 41 is formed in one part of its periphery with a recess 54 which defines side wall cams 55 and 56 on opposite side walls of the drum 4] and a groove-like receiving portion 57 at the rear end of the periphery of the drum 4] and disposed parallel to the axis of the drum 41. The clamp member 51 is normally urged by the biasing forces of the aforementioned springs 52 and 53 into pressing engagement with valleys of the side wall earns 55 and 56 and the receiving portion 57 on the drum 4]. When the clamp member 51 is maintained in pressing engagement with the receiving portion 57 as aforementioned, the supporters 46 and 47 and the sheet feed cam 44 and mounting plate 45 which support the supporters 46 and 47 can rotate in the same direction as the drum 41 when the latter is driven.

In FIG. 6, grip claw means 59 adapted to grip the leading end portion of a sheet 64 is supported at its base by screws 62 to a shaft 61 loosely supported at opposite ends by the opposite side walls of the drum 4] and urged by the biasing force of a spring (not shown) to bring its front end into pressing engagement with an offset portion 58 formed at the front end of the periphery of the drum 41. A stopper 63 is secured at its base to the shaft 61 and formed at its free end with a bent portion 63a against which the sheet 64 abuts at its leading end to thereby position the sheet 64 relative to the drum 4] when a sheet is fed to the drum as subsequently to be described.

The offset portion 58 is contiguous with another offset portion 65 disposed at a lower level with which push-out means 66 is maintained in pressing engagement at its free end, the push-out means 66 being secured at its base to a lever 67. The lever 67 is pivotally connected at one end through a shaft 72 to the free end of an arm 71, and is formed therein with a slot 68 loosely receiving therein a pin 69 affixed to one side wall of the drum 4]. The arm 7] is pivotally supported at its base by a shaft 73 supported by the opposite side walls of the drum 41. When the arm 71 moves clockwise about the shaft 73 in a sheet discharge operation as subsequently to be described. the push-out means 66 move outwardly of the periphery of the drum 41 to thereby push the leading end portion of the sheet 64 away from the drum 41.

In FIG. 4, a strip claw 75 for picking the sheet 64 off the periphery of the drum 4] and a sheet feed tray 76 are disposed rightwardly of the drum 41. A sheet feed roller 77 is disposed above the sheet feed tray 76 and a sheet discharge roller 78 is disposed below the sheet feed tray 76, and an actuation roller 79 is interposed between the feed and discharge rollers 77 and 78. As shown in FIG. 17, the actuation roller 79 comprises major diameter portions 790 adapted to be rendered operative when sheet feed is carried out and minor diameter portions 79b adapted to be rendered operative when sheet discharge is carried out. Normally the minor diameter portions 79b are maintained in pressing engagement with the sheet discharge roller 78.

The actuation roller 79 is secured to a shaft 82 rotatably supported by a free end ofa support arm 81 which is secured at its base to a shaft 83 supported by the left and right side plates. The sheet feed tray 76 is formed therein with an opening 84 permitting the major diameter portions 790 (See FIG. 17) of the actuation roller to move thercthrough into engagement with the periphery of the sheet feed roller 77 when the support arm 81 moves clockwise about the shaft 83.

As shown in FIG. 8, a gear 85 is rotatably mounted at an end portion of the shaft 83 and maintained in meshing engagement with pinions 86 and 87 which are secured to shafts 88 and 89 respectively. The sheet feed roller 77 is secured to the shaft 88 while the sheet discharge roller 78 is secured to the shaft 89. A sprocket wheel 91 is secured to one side of the gear 85 and another sprocket wheel 92 is mounted on the shaft 42 supporting the drum 4], with a chain 93 being trained over the two sprocket wheels 91 and 92. As a result. when the drum 41 rotates in the direction of the arrow 43, the pinions 86 and 87 and the sheet feed and discharge rollers 77 and 78 (See FIG. 4) which act as a unit with the pinions 86 and 87 respectively rotate idly in the directions of arrows 94 and 95 respectively.

A copy sheet feed cam follower 96 shown in FIG. 7 is secured at its base to an end portion of the shaft 83 to which the support arm 81 is secured as shown in FIG. 4. The mechanism including the follower 96 shown in FIG. 7 is disposed outwardly of one of the side plates of the duplicating machine. A sheet feed cam 97 adapted to actuate the sheet feed roller 77 is secured to the shaft 42 supporting the drum 41 and rotates in the same direction as the drum 4]. A roller 98 supported through a shaft by the follower 96 at its free end is positioned against the periphery of the cam 97. The follower 96 is formed at its shorter arm with a bent portion 99 which is normally maintained in locking engagement with an engaging portion 102 of a sheet feed first actuation member 101 so as to preclude movement of the follower 96 in slaved relation to the cam 97 as the latter rotates.

The first actuation member 101 is pivotally sup ported by a shaft 103 connected to one of the side plates of the machine and normally urged to move counter clockwise about the shaft 103 by the biasing force of a spring 104 connected at one end to the member 10] and at the other end to the side plate. Normally a lower end portion of the member 101 is maintained in engagement with the bent portion 99 of the follower 96 to preclude the movement of the follower 96.

A spring 105 is connected at one end to a right end portion of the first actuation member 101 and at the other end to an actuator 107 for a sheet feed solenoid 106. Disposed below the follower 96 is a sheet feed second actuation member 108 which is secured at its base to a shaft 109 (See FIG. 14) loosely supported by the side plates of the machine. A spring 113 is connected at one end to a free end of the member 108 and at the other end to an actuator 112 for a sheet discharge solenoid 111. A stopper 114 for limiting the range of move ment of the member 108 is disposed below the latter. A spring 115 for returning the member 108 to its original position is connected at one end to the member 108 and at the other end to the side plate of the machine.

A loop 118 attached to one end of a connector 117 is hitched to a pin 116 affixed to the second actuation member 108. The connector 117 is pivotally supported at the other end by a pin 119 affixed to the first actuation member 101 which is formed at its upper left end with a hook 12] adapted to engage a pin 123 affixed to one end portion of a short arm 122. A compression spring 124 is connected at one end to the other end of the short arm 122 and at the other end to the follower 96. The short arm 122 is secured to a shaft 125 loosely supported by the side plates of the machine. The shaft 125 also supports a pair of lock levers 126 at their bases.

In FIG. 4, one of the lock levers 126 is shown as being formed at its free end with a hook 127 adapted to catch hold of a pin 128 affixed to the clamp member supporter 46 to temporarily interrupt the movement of the supporter 46. When the short arm 122 (See FIG. 7) is engaged by the first actuation member 101, the hook 127 is disposed in a position in which it is spaced apart from the path of movement of the pin 128 affixed to the supporter 46.

In FIG. 4, a sheet discharge cam 131 is secured at its base to the shaft 109 to which the second actuation member 108 is secured as shown in FIG. 7. The sheet discharge cam 131 is urged by the biasing force of the spring 115 (See FIG. 7) to bring its lower side edge into pressing engagement with a shaft 133 which pivotally supports a release member 132. A pin 134 affixed to an end portion of the release member 132 is maintained in pressing engagement with the sheet discharge cam 131 by the biasing force of a compression spring 136 connected at one end to the pin 134 and at the other end to a pin affixed to the sheet discharge cam 13].

A sheet feed follower 138 is secured at its base as shown in FIG. 4 to an end portion of the shaft 61 mounting the grip claw means 59 as shown in FIG. 5 and FIG. 6. A roller 139 supported through a shaft by the follower 138 at its free end is positioned against the periphery of the sheet feed cam 44. A sheet discharge follower 141 is secured as shown in FIG. 4 to an end portion of the shaft 73 mounting the arm 71 as shown in FIG. 6. The follower 141 supports at one end through a shaft a roller 142 adapted to cooperate with the sheet discharge cam 13], and is positioned at the other end against a pin 145 affixed to the underside of the follower 138.

As shown in FIG. 15, a lever 146 is secured at its base to the shaft 133 mounting the release member 132, and

supports at its free end a sheet discharge guide roller I47 which is normally disposed in a position in which it is spaced apart from the periphery of the drum 4] as shown in a phantom line at 148.

When the sheet 64 is set at a position in which its leading end portion is disposed against an offset portion 76a of the sheet feed tray 76 and the drum 41 is brought to the position shown in FIG. 4, instructions to feed a sheet are given to the solenoid 106 (See FIG. 7) which is energized and moves the first actuation member 101 clockwise about the shaft 103. This releases the bent portion 99 of the follower 96 and the pin 123 disposed on the short arm 122, and the roller 98 supported by the follower 96 is brought into engagement with a minor diameter portion 970 of the cam 97 as the latter rotates, so that the follower 96 slightly moves clockwise from the position shown in FIG. 7 to the position shown in FIG. 9.

At this time, the support arm 81 (See FIG. 4) adapted to move as a unit with the follower 96 moves clockwise about the shaft 83 into the position shown in FIG. 10. This causes the major diameter portions 79a of the actuation roller 79 to bring the leading end portion of the sheet 64 into pressing engagement with the sheet feed roller 77. Thus the sheet 64 is fed to the drum 4i by the sheet feed roller 77 rotating in the direction of the arrow 94 at all times and the actuation roller 79 rotating in slaved relation to the sheet feed roller 77.

On the other hand, actuation of the first actuation member 101 releases the short arm 122 and permits the same to move counter clockwise as shown in FIG. 9. This results in the lock lever 126 also moving counter clockwise and catching hold of the pin 128 affixed to the clamp member supporter 46 by its hook 127. Likewise, the clamp member supporter 47 shown in FIG. 5 is engaged and locked by another lock lever (not shown) by its hook. As a result, the clamp member supporters 46 and 47 and the sheet feed cam 44 and mounting plate 45 supporting the supporters 46 and 47 are kept from rotating with the drum 4] although the latter is free to rotate, so that the roller 139 supported by the follower 138 moves over a crest 440 at the periphery of the cam 44. Thus the follower 138 makes one revolution about the shaft 42 and moves the grip claw means 59 between its open and closed positions to thereby clamp the leading end portion of the sheet 64 to the periphery of the drum 4] as shown in FIG. 11 and FIG. 6.

The clamp member 51 moves from the valleys of the side wall earns 55 and 56 to their crests and along the periphery of the drum 4]. Thus the sheet 64 moves under the clamp member 51 and rotates with the drum 4].

The sheet feed solenoid 106 shown in FIG. 7 remains emergized for a short time interval. After releasing the follower 96 and short arm 122, the first actuation member 10] tends to be restored to its original position by the biasing force of the spring I04. Thus, when the follower 96 is restored to its original position by the rotating cam 97. the first actuation member 101 is also restored to its original position as shown in FIG. I] and locks the follower 96. That is, after the leading end portion of the sheet 64 is clamped to the periphery of the drum 4], the actuation roller 79 is returned from the position shown in FIG. 10 to the position shown in FIG. 4, thereby ending the feeding of the sheet 64.

As soon as the drum 4! makes one complete revolution after the clamp member supporters 46 and 47 are locked and restrained from rotating with the drum 4], the clamp member 51 is brought into engagement with the valleys of the side wall earns 55 and 56 and the receiving portion 57 (See FIG. 6) on the drum 4] so as to clamp a trailing end portion 640 of the sheet 64 (See FIG. 6) to the periphery of the drum 41 as shown in FIG. 13. The clamp member 51 performs the aforementioned clamping function as the clamp members supporters 46 and 47 supporting the clamp member 51 are urged by the springs 52 and 53 respectively to move toward the center axis of the drum 41 and are restored to their original positions.

As soon as the trailing end portion 640 of the sheet 64 is clamped by the clamp member 51, the pin 128 on the supporter 46 is released from engagement with the hook 127 and the supporters 46 and 47 are released from the restraint imposed thereon. As a result, the cam 44 and mounting plate 45 on which the supporters 46 and 47 are mounted respectively are free to rotate with the drum 41 in the same direction. Thus duplicating or copying is carried out while the sheet 64 is maintained in intimate contact with periphery of the drum as the leading end portion and trailing end portion thereof are positively clamped to the drum.

The sheet discharge solenoid 111 shown in FIG. 7 is energized when instructions are given to discharge the sheet 64 from the drum 41. When the solenoid 111 shown in FIG. 7 is energized, the second actuation member 108 moves clockwise about the shaft 109 and the sheet discharge cam 131 (See FIG. 4) adapted to act as a unit with the member 108 also moves clockwise. As a result, the pin 134 on the release member 132 is brought into engagement with an offset portion 137 formed in the cam 131 and the release member 132 moves counter clockwise about the shaft 133, so that the cam 131 and release member 132 moves from their positions shown in FIG. 4 to their positions shown in FIG. 14. As the release member 132 moves counter clockwise as aforementioned, the lever 146 adapted to move as a unit with the member 132 also moves counter clockwise to its position shown in FIG. 15, so as to bring the guide roller 147 into pressing engagement with the periphery of the drum 41.

The sheet discharge solenoid lll remains energized for a short time interval. Thus restoration of the second actuation member 108 and sheet discharge cam 131 by the biasing force of the spring is precluded by the pin 134 on the release member 132 being maintained in pressing engagement with the offset portion 137 of the sheet discharge cam 13] (See FIG. 7). Actuation of the second actuation member 108 moves the first actuation member 101 clockwise through the connector 117 to its position shown in FIG. 14. At this time, the first actuation member 10] moves to an extent such that the bent portion 99 of the follower 96 is not released from engagement with the engaging portion I02 of the member 101. As a result, the follower 96 is restrained by the first actuation member 101 although the short arm 122 secured to the shaft supporting the lock levers I26 is released. Thus the support arm 81 adapted to act as a unit with the follower 96 remains in its position shown in FIG. 4, so that the minor diameter portions 79b of the actuation roller 79 rotate counter clockwise in slaved relation while being maintaincd in pressing engagement with the sheet discharge roller 78.

FIG. 14 shows the elements involved in sheet dis charge being ready for action. Rotation of the drum 41 in the direction of the arrow 43 results in the roller 142 being pushed and moved by an upper side edge 131a of the sheet discharge cam I31 toward the central portion of the drum 41 as shown in FIG. 16. That is, the follower I41 supporting the roller I42 moves clockwise about the shaft 73 into a position shown in FIG. 16 in which it pushes and moves at its free end the pin 145 so as to cause the follower I38 mounting the pin 145 to move counter clockwise about the shaft 61. As a result, the grip claw means 59 adapted to move as a unit with the follower 138 is brought to an open position and releases the leading end portion 64b of the sheet 64.

When the follower 14] moves clockwise as aforementioned, the arm 71 (See FIG. 6) adapted to act as a unit with the follower 141 also moves clockwise and moves the free end of the pushout means 66 outwardly so as to push the leading end portion 64b outwardly of the periphery of the drum 41. After being pushed out in this way, the leading end portion 64b is picked off the periphery of the drum 4] by the pick-off claw 7S and guided by the sheet discharge roller 78 and the minor diameter portions 79a of the actuation roller 79 to move in the direction of an arrow as shown in FIG. 18.

As the follower 141 further moves about the shaft 42 in FIG. I6, the roller 142 kicks a free end 132a of the release member 132 disposed in the path of movement of the roller 142 and restores the release member 132 to its original position as shown in FIG. 18. As a result, the guide roller 147 is moved away from the periphery of the drum 41 and the sheet discharge cam 131 is released from restraint, so that the cam 131 and the second actuation member 108 adapted to act as a unit with the cam 131 are restored to their original positions by the biasing force of the spring 115 (See FIG. 7).

On the other hand. the pin 128 on the clamp member supporter 46 shown in FIG. 14 is again caught hold of by the hook 127 of the lock lever 126, so that the clamp member supporters 46 and 47 are kept from rotation. As a result, the clamp member 51 slides on the periphcry of the drum 41 as shown in FIG. II in the same manner as described with reference to feeding of the sheet 64 to the drum 4], thereby releasing the trailing end portion 64a of the sheet 64 which has been clamped by the member 51 to the receiving portion 57 (See FIG. 6) on the periphery of the drum 4]. The clamp member supporters 46 and 47 are restored to their original positions as the clamp member 51 is again brought into engagement with the receiving portion 57 after the drum 41 has made one complete revolution. Thus all the mechanisms are restored to their initial positions shown in FIG. 4.

FIG. 19 and FIG. 2| show other embodiments of the invention. In these figures and FIG. 4, like reference characters designate similar parts which function in the same manner. In FIG. 19, a pair of cams I51 (only one cam being shown) are each secured to one of the two sides of the drum 4]. A clamp member 153 is main taincd in engagement with a recess 152 formed by side edges 151 of the cams 151 (only one side edge 1511: being shown) and the receiving portion 57 on the periphery of the drum 41. The clamp member 153 is sup ported at opposite ends by a pair of clamp member supporters 154 (only one supporter being shown) at their free end. The clamp member supporters 154 are each pivotally supported at their base by a shaft 156 which supports the free end of a support arm 155 pivotally supported at its base by the shaft 42 supporting the drum 41. Each supporter 154 is urged to move clockwise about the shaft 156 by the biasing force of a spring 157 connected at one end to the supporter 154 and at the other end to the support arm 155.

The cams 151 perform the same function as the side wall cams and 56 shown in FIG. 5, and the clamp member 153 performs the same function as the clamp member 51 and pin 128 shown in FIG. 4. When sheet feed instructions are given, the lock lever 126 moves counter clockwise from the position shown in FIG. 19. As a result, the clamp member 153 moving in the direction of the arrow 43 together with the drum 41 is engaged and locked by the hook 127, so that the supporters 154 and support arms are restrained from moving with the drum 41.

On the other hand, the clamp member 153 kept from moving with the drum 41 moves along an edge 151a of each cam 151, so that it is released from engagement with the recess 152 and brought into engagement with the upper surface of the sheet 64 fed to the periphery of the drum 41 as shown in FIG. 20. One complete rotation of the drum 41 brings the clamp member 153 into engagement with the recess 152 again, so that the trailing end portion of the sheet 64 is clamped by the clamp member 153 to the periphery of the drum 41.

In FIG. 21, a pair of cams 161 (only one cam being shown) are each secured to one of the two sides of the drum 41. Each cam 161 has a major diameter portion I6la with which a roller 162 is maintained in pressing engagement. The roller 162 is supported at one end portion of a clamp member supporter 163 which is pivotally supported substantially at its central portion by a shaft 165 connected to the free end of a support arm I64 pivotally supported at its base by the shaft 42 supporting the drum 41. The supporter 163 is urged to move counter clockwise about the shaft 165 by the biasing force of a spring 166 connected at one end to the support arm 164 and at the other end to the cam 161. The supporter 163 is formed at the other end portion with an inwardly bent portion 163a which is maintained in pressing engagement with a recess 167 formed on the periphery of the drum 41 and having a resilient member 168 embedded therein. The inwardly bent portion 163a presses against the resilient member 168 when the roller 162 is maintained in engagement with the major diameter portion 1610 of the cam 161.

A hold-down roller 169 is disposed above the periphery of the drum 41. The roller 169 is adapted to be brought into pressing engagement with the periphery of the drum 41 when a sheet is fed to the drum, but is normally disposed in a position in which it is spaced apart from the periphery of the drum 41. The clamp member supporter 163 has affixed thereon a pin 171 which is adapted to be engaged and locked by the hook 127 of the lock lever 126 (See FIG. 4 and FIG. 19) when the latter is moved to its operative position.

When instructions are given to feed a sheet and the sheet 64 is gripped at is leading end portion by grip means disposed on the periphery of the drum 41. the pin 17] on the supporter 163 is engaged by the hook 127, so that the supporter 163 and support arm 164 are kept from moving with the drum 41, and only the drum 41 rotates in the direction of the arrow 43. As a result. the roller 162 is brought into engagement with a minor diameter portion 16lb of the earn 161 as shown in FIG. 22 and the supporter 163 moves counter clockwise about the shaft 165. At the same time, inwardly bent portion 163a of the clamp member supporter 163 is released from engagement with the recess 167. The sheet 64 moves under the inwardly bent portion 1630 as shown in FlG. 22 and is brought into intimate contact with the periphery of the drum 41 by the holddown roller 169. The sheet 64 has its trailing end portion clamped by the inwardly bent portion 16311 of the supporter 163 to the drum 4] as the inwardly bent portion 163a is again brought into engagement with the recess 167 on the periphery of the drum 41 after the drum has made one complete revolution. At the same time, the hold-down roller 169 is moved from its operative position on the periphery of the drum 41 to its inoperative position in which it is spaced apart from the drum 41 by suitable means (not shown).

Means for supporting and actuating the clamp member for clamping the trailing end portion of the sheet 64 may comprise, in addition to the clamp member supporters 46 and 47 shown in FIG. 4, the clamp member supporters 154 adapted to be actuated by the cams 151 as shown in FIG. 19 and the clamp member supporters 163 adapted to be actuated by the cams 161 as shown in FIG. 21. Means for clamping the trailing end portion of the sheet 64 to the drum 41 may comprise, in addition to the clamp member 51 shown in H0. 4, the clamp member 153 shown in FIG. 19 and the inwardly bent portions 1630 of the clamp member supporters 163 shown in H0. 21.

What is claimed is:

1. In a duplicating machine, wherein the leading margin of a sheet is clamped to the periphery of a rotary drum and the sheet is positioned about the periphery of the drum, the improvement comprising:

a. means defining an elongated recessed portion in the periphery of the drum disposed parallel to the axis of the drum and adapted to receive the trailing margin of the sheet after the sheet is positioned about the periphery of the drum;

b. an elongated clamp member disposed parallel to the recessed portion and adapted for movement into and out of engagement with the recessed portion; and

c. means for moving the elongated clamp member out of the recessed portion while the sheet is being positioned about the periphery of the drum and for moving the elongated clamp member into engagement with the recessed portion while the trailing margin is disposed therein after the sheet has been positioned about the periphery of the drum to clamp the trailing margin to the periphery of the drum. wherein said means for moving the elongated elamp member into and out of engagement with the recessed portion comprises a pair of supporters each holding one of the opposite ends of the clamp member and mounted on one of the opposite ends of the drum for rotational and radial movement relative to the drum, means for restraining the supporters from rotating while the leading margin of the sheet is being clamped to the periphery of the drum, cam means for moving the supporters radially of the drum while the supporters are restrained from rotating so as to move the clamp member radially outwardly from the periphery of the drum, and cam means for releasing the supporters for rotational movement together with the drum after the trailing margin of the sheet is held in the recessed portion.

2. A device according to claim 1 wherein said means for restraining the supporters from rotating comprises at least one lock lever pivotally supported at a fixed base and having a hook at its free end for catching one of the supporters.

3. In a duplicating machine, wherein the leading margin of a sheet is clamped to the periphery of a rotary drum and the sheet is positioned about the periphery of the drum, the improvement comprising:

a. means defining an elongated recessed portion in the periphery of the drum disposed parallel to the axis of the drum and adapted to receive the trailing margin of the sheet after the sheet is positioned about the periphery of the drum;

b. an elongated clamp member disposed parallel to the recessed portion and adapted for movement into and out of engagement with the recessed portion; and

c. means for moving the elongated clamp member out of the recessed portion while the sheet is being positioned about the periphery of the drum and for moving the elongated clamp member into engagement with the recessed portion while the trailing margin is disposed therein after the sheet has been positioned about the periphery of the drum to clamp the trailing margin to the periphery of the drum, wherein said means for moving the elongated clamp member into and out of engagement with the recessed portion comprises a pair of support arms each mounted on one of the opposite ends of the drum for rotational movement relative to the drum, a pair of supporters each holding at its free end one of the opposite ends of the clamp member and pivotally connected at its base to one of said support arms, means for restraining the supporters from rotating while the leading margin of the sheet is being clamped to the periphery of the drum, cam means for moving the supporters radially of the drum while the supporters are restrained from rotating so as to move the clamp member radially outwardly from the periphery of the drum, and means for releasing the supporters for rotational movement together with the drum after the trailing margin of the sheet is held in the recessed portion.

4. A device according to claim 3 wherein said means for restraining the supporters from rotating comprises at least one lock lever pivotally supported at a fixed base and having a hook at its free end for catching the clamp member.

5. A device according to claim 3 further comprising a resilient member disposed in the recessed portion of the drum and positioned to be engaged by the clamp member to firmly hold the trailing margin of the sheet. 

1. In a duplicating machine, wherein the leading margin of a sheet is clamped to the periphery of a rotary drum and the sheet is positioned about the periphery of the drum, the improvement comprising: a. means defining an elongated recessed portion in the periphery of the drum disposed parallel to the axis of the drum and adapted to receive the trailing margin of the sheet after the sheet is positioned about the periphery of the drum; b. an elongated clamp member disposed parallel to the recessed portion and adapted for movement into and out of engagement with the recessed portion; and c. means for moving the elongated clamp member out of the recessed portion while the sheet is being positioned about the periphery of the drum and for moving the elongated clamp member into engagement with the recessed portion while the trailing margin is disposed therein after the sheet has been positioned about the periphery of the drum to clamp the trailing margin to the periphery of the drum, wherein said means for moving the elongated clamp member into and out of engagement with the recessed portion comprises a pair of supporters each holding one of the opposite ends of the clamp member and mounted on one of the opposite ends of the drum for rotational and radial movement relative to the drum, means for restraining the supporters from rotating while the leading margin of the sheet is being clamped to the periphery of the drum, cam means for moving the supporters radially of the drum while the supporters are restrained from rotating so as to move the clamp member radially outwardly from the periphery of the drum, and cam means for releasing the supporters for rotational movement together with the drum after the trailing margin of the sheet is held in the recessed portion.
 2. A device according to claim 1 wherein said means for restraining the supporters from rotating comprises at least one lock lever pivotally supported at a fixed base and having a hook at its free end for catching one of the supporters.
 3. In a duplicating machine, wherein the leading margin of a sheet is clamped to the periphery of a rotary drum and the sheet is positioned about the periphery of the drum, the improvement comprising: a. means defining an elongated recessed portion in the periphery of the drum disposed parallel to the axis of the drum and adapted to receive the trailing margin of the sheet after the sheet is positioned about the periphery of the drum; b. an elongated clamp member disposed parallel to the recessed portion and adapted for movement into and out of engagement with the recessed portion; and c. means for moving tHe elongated clamp member out of the recessed portion while the sheet is being positioned about the periphery of the drum and for moving the elongated clamp member into engagement with the recessed portion while the trailing margin is disposed therein after the sheet has been positioned about the periphery of the drum to clamp the trailing margin to the periphery of the drum, wherein said means for moving the elongated clamp member into and out of engagement with the recessed portion comprises a pair of support arms each mounted on one of the opposite ends of the drum for rotational movement relative to the drum, a pair of supporters each holding at its free end one of the opposite ends of the clamp member and pivotally connected at its base to one of said support arms, means for restraining the supporters from rotating while the leading margin of the sheet is being clamped to the periphery of the drum, cam means for moving the supporters radially of the drum while the supporters are restrained from rotating so as to move the clamp member radially outwardly from the periphery of the drum, and means for releasing the supporters for rotational movement together with the drum after the trailing margin of the sheet is held in the recessed portion.
 4. A device according to claim 3 wherein said means for restraining the supporters from rotating comprises at least one lock lever pivotally supported at a fixed base and having a hook at its free end for catching the clamp member.
 5. A device according to claim 3 further comprising a resilient member disposed in the recessed portion of the drum and positioned to be engaged by the clamp member to firmly hold the trailing margin of the sheet. 